The present invention relates to an elastic wheel for use in a wheel of a vehicle, and more particularly, to an elastic wheel which has superior riding comfort and vibration proofing and sound proofing performances, and with which a car can be driven with high safety even when the inner pressure is reduced.
Generally, elastic wheels have a disk fixed to an axle hub and a rim supporting a tire, respectively. There have been proposed different types of elastic wheels in which vibration-isolators are provided between disks and rims for enhancement of the vibration isolating performance and the riding comfort. For example, Japanese Unexamined Utility Model Publication No. 59-188701 purposes a tire wheel which uses a spring as a vibration isolator for enhancement of riding comfort.
Moreover, there have been wheels in which as vibration isolators, rubber is arranged between rims and disks. For example, an elastic wheel having a structure in which the rim is connected to the disk via a rubber elastic member is proposed in Japanese Unexamined Utility Model Publication No. 57-73203. Moreover, Japanese Unexamined Patent Application Publication No. 5-338401 discloses an elastic wheel in which a gap is formed between the rim and the elastic wheel, and a vibration isolating rubber is provided in the gap. Furthermore, WO Publication No. 98/33666 discloses a wheel barrier assembly in which an annular strip made of rubber is arranged between a rim and an inner rim having the same profile as the rim.
However, in the case of conventional elastic wheels using rubber as vibration isolators which are uniformly arranged between rims and disks, an elastic rubber body is arranged between the inner peripheral surface of a rim and the outer peripheral surface of a disk and bonded to them by vulcanization. Thus, vibrations in the axial direction, the radial direction, and the rotation direction, transmitted from the rim to the disk via the elastic rubber body, can be adequately suppressed. However, there are problems in that the displacement of the elastic rubber body caused by large loads can not be inhibited. That is, it has been difficult to obtain adequate vibration isolating characteristics in the range of from small input to large input, respectively, since the rubber cross-section is uniform. In this point, similar problems are caused in wheels having springs as vibration-isolators.
Relations of rubbers arranged between rims and disks to their sound proofing performances have not completely been revealed. The sound proofing performance should be still improved.
On the other hand, for run-flat tires, it has been necessary to reinforce the structure of a tire itself. Thus, there are problems in that the tire becomes expensive, the rolling resistance is increased, and the riding comfort is deteriorated, that is, the performances required for ordinary use are deteriorated. Moreover, it has been difficult to develop run-flat tires which are durable to driving a long distance after the tires blow out. Accordingly, it has been investigated to use a run-flat tire and a special wheel in combination. However, no conventional techniques sufficiently take into account the vibration performance and the riding comfort. On the other hand, elastic wheels which are produced for use in run-flat tires and can enhance the above-described performances have not been known. Thus, the structures of the elastic wheels are not durable to run-flat driving.
Accordingly, it is an object of the present invention to provide an elastic wheel of which the riding comfort, and the vibration-proofing and sound-proofing performances are enhanced in the range of from small input to large input without the service life and the safety being deteriorated.
It is another object of the present invention to provide an elastic wheel of which the riding comfort, and the vibration-proofing and sound-proofing performances are enhanced in the range of from small input to large input without the service life and the safety being deteriorated, and which realizes both of the run-flat performances and the riding comfort.
The inventors have extensively investigated to solve the above-described problems, making the most of the properties of an elastic rubber body as a vibration isolator, and have found that the above-described objects can be achieved by the following constitution. Thus, the present invention has been devised. The elastic wheel of the present invention is as follows.
That is, an elastic wheel of the present invention comprises a disk having a base rim and a rim supporting a tire, wherein a projected part with a generally trapezoidal cross-section in the wheel axis direction is formed in a well of the rim, and a pair of elastic rubber bodies are provided annularly between the outer surfaces of a pair of wall parts formed by bending the both sides of the base rim at a sharp angle and the rim inner peripheral surface of the generally trapezoidal projected part.
Thereby, vibration can be absorbed by both the shearing deformation and the compressive deformation of the installed elastic rubber bodies, and riding comfort, vibration proofing, and sound proofing performances in the range of from small input to large input can be enhanced. Moreover, the sound proofing performance is very effective for sound in a high frequency area of 100 Hz or higher.
Preferably, the generally trapezoidal shape is an isosceles trapezoid. Also, preferably, the angle xcex21 defined by a leg portion constituting the generally trapezoidal shape and the equatorial plane E of the wheel is substantially equal to the angle xcex11 defined by the outer peripheral surface of one of the wall parts and the equatorial plane E of the wheel. Moreover, preferably, both of the angles xcex11 and xcex21 are in the range of 0xc2x0 to 60xc2x0. Furthermore, both of the outer end portions in the tire radial direction of the wall parts formed on the both sides of the base rim are connected to each other so as to form a trapezoidal cross-section substantially similar to the generally trapezoidal shape of the rim in the wheel axial direction, and an elastic rubber body is annularly formed between the outer peripheral surface of the plateau portion of the base rim and the inner peripheral surface of the plateau portion of the rim with a gap being formed with respect to one of the outer peripheral surface and the inner peripheral surface. Thereby, even if very large input is applied, large deformation can be prevented, due to the compression action of the elastic rubber body as a stopper provided on the outer peripheral surface of the base rim or the inner peripheral surface of the rim.
Moreover, an elastic wheel of the present invention comprises a disk having a base rim and a rim supporting a tire, wherein a projected part with a semi-circular cross-section in the wheel axis direction is formed in a well of the rim, and a pair of elastic rubber bodies are provided annularly between the outer surfaces of a pair of wall parts formed by bending the both sides of the base rim correspondingly to the semi-circular shape and the rim inner peripheral surface of the semi-circular projected part.
Thereby, vibration can be absorbed by both the shearing deformation and the compressive deformation of the installed elastic rubber bodies, and riding comfort, vibration proofing, and sound proofing performances in the range of from small input to large input can be enhanced. Moreover, the sound proofing performance is very effective for sound in a high frequency area of 100 Hz or higher.
Preferably, both of the outer end portions in the tire radial direction of the wall parts formed on the both sides of the base rim are connected to each other so as to form a semi-circular cross-section in the wheel axis direction substantially similar to the semi-circular shape of the rim, and an elastic rubber body is annularly formed in the center area between the semi-circular outer peripheral surface of the base rim and the semi-circular inner peripheral surface of the rim with a gap being formed with respect to one of the outer peripheral surface and the inner peripheral surface. Thereby, even if very large input is applied, large deformation can be prevented, due to the compression action of the elastic rubber body as a stopper provided on the outer peripheral surface of the base rim or the inner peripheral surface of the rim.
Furthermore, an elastic wheel of the present invention comprises a disk having a base rim and a rim supporting a tire, wherein the wheel includes a pair of guides annularly fixed to the inner peripheral surface of the rim and a pair of wall parts annularly fixed in the both-side areas in the tire axial direction of the outer peripheral surface of the base rim, elastic rubber bodies are annularly formed between the side-surfaces of the guides and the side-surfaces of the wall parts, respectively, and both of the angle xcex22 defined by the side surface of one of the guides and the equatorial plane of the wheel and the angle xcex12 defined by the side surface of one of the wall parts and the equatorial plane of the wheel are in the range of 0xc2x0 to 60xc2x0.
Thereby, vibration can be absorbed by both the shearing deformation and the compressive deformation of the installed elastic rubber bodies, and riding comfort, vibration proofing, and sound proofing performances in the range of from small input to large input can be enhanced. Moreover, the sound proofing performance is very effective for sound in a high frequency area of 100 Hz or higher.
Furthermore, an elastic wheel of the present invention comprises a disk having a base rim and a rim supporting a tire, wherein a projected part with a generally trapezoidal cross-section in the wheel axis direction is formed in a well of the rim, a pair of elastic rubber bodies are provided annularly between the outer surfaces of a pair of wall parts formed by bending the both sides of the base rim at a sharp angle and the rim inner peripheral surface of the generally trapezoidal projected part, and a thick elastic rubber body is annularly formed on the outer peripheral surface of the plateau portion of the generally trapezoidal projected part.
Thereby, vibration can be absorbed by both the shearing deformation and the compressive deformation of the installed elastic rubber bodies, and riding comfort, vibration proofing, and sound proofing performances in the range of from small input to large input can be enhanced. Moreover, the sound proofing performance is very effective for sound in a high frequency area of 100 Hz or higher. When the inner pressure of a tire is reduced caused by blowing out or the like, so-called run-flat running can be achieved, due to the present of the thick elastic rubber body. In this case, the riding comfort can be also enhanced by the vibration-absorbing action caused by the shearing deformation and the compressive deformation of the elastic rubber body.
Preferably, the generally trapezoidal shape is an isosceles trapezoid. Also, preferably, the angle xcex2 defined by one of the rim inner peripheral surfaces constituting the leg portions of the wall parts and the equatorial plane of the wheel is substantially equal to the angle xcex1 defined by the one of the outer peripheral surfaces of the wall parts and the equatorial plane of the wheel. Moreover, preferably, both of the angles xcex1 and xcex2 are in the range of 0xc2x0 to 60xc2x0.
Furthermore, preferably, both of the outer end portions in the tire radial direction of the wall parts formed on the both sides of the base rim are connected to each other so as to form a trapezoidal cross-section in the wheel axial direction substantially similar to the generally trapezoidal shape of the rim in the wheel axial direction, and an elastic rubber body is annularly formed between the outer peripheral surface of the plateau portion of the base rim and the inner peripheral surface of the plateau portion of the rim with a gap being formed with respect to one of the outer peripheral surface and the inner peripheral surface. Thereby, even if very large input is applied, large deformation can be prevented, due to the compression action of the elastic rubber body as a stopper provided on the outer peripheral surface of the base rim or the inner peripheral surface of the rim. Especially, this is effective in run-flat driving.